19 January 2009More evidence linking water pollution to sub-fertilityby George Atkinson

Appearing in the journal Environmental Health Perspectives, new research from the UK shows how testosterone-blocking chemicals are finding their way into waterways, strengthening the link between water pollution and rising male fertility problems.

The study identified a group of chemicals that act as "anti-androgens," which inhibit the function of testosterone and reduce male fertility. Some of the chemicals in question can be found in over-the-counter medicines, pharmaceutical treatments and pesticides.

Past research has shown how female hormones like estrogen, and chemicals that mimic estrogen, can trigger the "feminization' of male fish in rivers and streams. This causes reproductive problems by reducing fish breeding capability and in some cases can lead to male fish changing gender.

Other studies have also suggested that there may be a link between this phenomenon and the increase in human male fertility problems caused by testicular dysgenesis syndrome and the new study firms up this link. "We have identified a new group of chemicals in our study on fish, but do not know where they are coming from. A principal aim of our work is now to identify the source of these pollutants and work with regulators and relevant industry to test the effects of a mixture of these chemicals and the already known environmental estrogens and help protect environmental health," said study author Dr Susan Jobling, from Brunel University.

"Our research shows that a much wider range of chemicals than we previously thought is leading to hormone disruption in fish. This means that the pollutants causing these problems are likely to be coming from a wide variety of sources. Our findings also strengthen the argument for the cocktail of chemicals in our water leading to hormone disruption in fish, and contributing to the rise in male reproductive problems. There are likely to be many reasons behind the rise in male fertility problems in humans, but these findings could reveal one, previously unknown, factor," explained co-researcher Professor Charles Tyler, of the University of Exeter.

The research team is now focusing on identifying the source of anti-androgenic chemicals, as well as continuing to study their impact on reproductive health in wildlife and humans.